Profiles of Proteinases in Gouda-Type Cheese

The pH of buffers used for extraction of proteinases from Gouda-type cheese affected the kinds of extractable proteinases. Proteinases in the fractions extracted with pH 3.0, 4.0, and 6.0 buffers were separated by CM-Sephadex or diethylaminoethyl-cellulose. Two (F3-I and F3-II), three (F4-I, F4-II, and F4-III), and one (F6) proteinases were separated from the pH 3.0, 4.0, and 6.0 extracts. The F3-I was completely inhibited by pepstatin. The F3-I degradated αs1- and β-casein into products with the same mobilities as αs1-casein(f24 to 199) and β-casein(f1 to 189) peptide, respectively. The F3-II was strongly inhibited by diisopropyl-fluorophosphate and soybean trypsin inhibitor, whereas F3-II produced fragments with mobilities equal to those of γ-caseins, that is, β-casein(f29 to 209), β-casein(f106 to 209), and β-casein (f109 to 209). The F4-I was completely inhibited by pepstatin as well as F3-I, but changes in the polyacrylamide gel electrophoresis pattern of casein by F4-II were different from those by F3-I. Properties of F4-II and F4-III were similar to those of F3-I and F3-II; therefore, F4-II and F4-III are considered to be the same enzymes as F3-I and F3-II, respectively. The F6 was strongly inhibited by diisopropyl-fluorophosphate and ethylenediaminetetraacetic acid. In Gouda-type cheese, there are at least four proteinases, two of them being serine proteinases and the other two acid proteinases.